Various types of unmanned or automatic guided vehicles are under development today. Such vehicles typically maneuver about an industrial facility via some navigation or guidance method, and are used to transport manufacturing items to and from various spaced apart locations or docking stations in the industrial facility. Typically, the docking stations include roller conveyors for loading and unloading cargo from a roller bed on the vehicle.
Such vehicles normally carry onboard computer systems which are in communication with a central facility computer. The central computer system directs the overall operation of the vehicle at a supervisory level, while the onboard computer performs local navigation tasks. At the local level, communication between the vehicle and a particular docking station is required to insure proper operation of the load management system.
The local communication system employed should be rugged for use in an industrial environment and not subject to interference from various noise sources within the environment. The availability of light emitting devices such as infrared light emitting diodes, and corresponding receiving devices such as phototransistors, offers a low cost and highly reliable solution to the communications problem.
Systems utilizing such optical devices have been proposed for other uses in the past. U.S. Pat. 4,025,791, issued to Lennington on May 24, 1977, teaches an optical interrogator and transponder device suitable for identifying a vehicle as it passes into a controlled area. U.S. Pat. No. 4,398,172, issued to Carroll et al. on Aug. 9, 1983, teaches a similar vehicle monitor apparatus. Other known optical communication systems include remote control units offered to operate with various television receivers.
Each of the above-identified devices provides an essentially one way communication system, with one device acting as a signal transmitter and the other as a receiver. Bidirectional communication is neither required nor provided for, yet the disclosed circuitry is quite complex, espensive to manufacture, and subject to failure in an industrial environment.
The present invention is directed to overcoming one or more of the problems as set forth above.